The invention relates to a detection device for detecting fires and/or signs of fire in a surveillance region using an imaging sensor element designed to output image data, the detection device comprising an optical device installed upstream of the sensor element, wherein the sensor element and the optical device in combination form a camera device for monitoring the surveillance region, and comprising an evaluation device designed to detect the fires and/or signs of fire in the surveillance region by evaluating the image data. The invention furthermore relates to a method for detecting fires and/or signs of fire.
Fire alarm systems include fire alarms as sensor devices for detecting fire, smoke, flames, or other signs of fire; they are used in public buildings such as schools or museums, and in private buildings. The majority of fire alarms may be divided roughly into two groups: a first group relates to point-type fire alarms which are used e.g. in offices or children's rooms, that is, in small spaces. Point-type fire alarms are typically installed on the ceiling, and they detect a fire or spreading smoke via optical, thermal, or chemical detection at exactly one point. These fire alarms have the advantage that the rising smoke that collects below the ceiling is detected very quickly. The disadvantage of these fire alarms is that a plurality of fire alarms must be used in larger spaces, e.g. warehouses, to ensure that the entire area is covered.
An alternative to this approach is provided by a second group of fire alarms that are designed as video fire-detection devices, in the case of which video surveillance systems are used that record a video image of a surveillance region using commercially available surveillance cameras and evaluate it in a surveillance center for the presence of fire or signs of fire.
Publication DE 10 246 056 A1 discloses a smoke alarm that includes an image recorder and a light source. This smoke alarm is used e.g. as a ceiling-mounted smoke alarm, and is designed such that the focal point of the image recorder is adjusted to be situated approximately 10 cm below the housing of the smoke alarm. If the illumination is poor, a light source can be activated in order to illuminate the focal point. In the case of smoke alarms of this type, since the focal point is nearby, background images are blurry as compared to images taken of the surroundings directly adjacent to the focal point.
Publication DE 100 114 11 A1, which represents the closest prior art, likewise relates to a fire alarm that uses a video camera or an infrared camera as the image recorder, the image recorder being adjusted such that a large camera viewing field and a life-like depiction of the observed scene are obtained. Fire is detected using object analysis, in which individual objects in the scene are analyzed automatically, in particular in terms of whether these objects are concealed by smoke, thermal inhomogeneities, or fire, the analysis being carried out by comparing the objects currently being recorded to stored objects.